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<a class="jxr_linenumber" name="1" href="#1">1</a>   <em class="jxr_comment">/*</em>
<a class="jxr_linenumber" name="2" href="#2">2</a>   <em class="jxr_comment"> * Copyright 2012 The Netty Project</em>
<a class="jxr_linenumber" name="3" href="#3">3</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="4" href="#4">4</a>   <em class="jxr_comment"> * The Netty Project licenses this file to you under the Apache License,</em>
<a class="jxr_linenumber" name="5" href="#5">5</a>   <em class="jxr_comment"> * version 2.0 (the "License"); you may not use this file except in compliance</em>
<a class="jxr_linenumber" name="6" href="#6">6</a>   <em class="jxr_comment"> * with the License. You may obtain a copy of the License at:</em>
<a class="jxr_linenumber" name="7" href="#7">7</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="8" href="#8">8</a>   <em class="jxr_comment"> *   <a href="http://www.apache.org/licenses/LICENSE-2.0" target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.0</a></em>
<a class="jxr_linenumber" name="9" href="#9">9</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="10" href="#10">10</a>  <em class="jxr_comment"> * Unless required by applicable law or agreed to in writing, software</em>
<a class="jxr_linenumber" name="11" href="#11">11</a>  <em class="jxr_comment"> * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT</em>
<a class="jxr_linenumber" name="12" href="#12">12</a>  <em class="jxr_comment"> * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the</em>
<a class="jxr_linenumber" name="13" href="#13">13</a>  <em class="jxr_comment"> * License for the specific language governing permissions and limitations</em>
<a class="jxr_linenumber" name="14" href="#14">14</a>  <em class="jxr_comment"> * under the License.</em>
<a class="jxr_linenumber" name="15" href="#15">15</a>  <em class="jxr_comment"> */</em>
<a class="jxr_linenumber" name="16" href="#16">16</a>  
<a class="jxr_linenumber" name="17" href="#17">17</a>  <em class="jxr_comment">/*</em>
<a class="jxr_linenumber" name="18" href="#18">18</a>  <em class="jxr_comment"> * Written by Doug Lea with assistance from members of JCP JSR-166</em>
<a class="jxr_linenumber" name="19" href="#19">19</a>  <em class="jxr_comment"> * Expert Group and released to the public domain, as explained at</em>
<a class="jxr_linenumber" name="20" href="#20">20</a>  <em class="jxr_comment"> * <a href="http://creativecommons.org/licenses/publicdomain" target="alexandria_uri">http://creativecommons.org/licenses/publicdomain</a></em>
<a class="jxr_linenumber" name="21" href="#21">21</a>  <em class="jxr_comment"> */</em>
<a class="jxr_linenumber" name="22" href="#22">22</a>  
<a class="jxr_linenumber" name="23" href="#23">23</a>  <strong class="jxr_keyword">package</strong> org.jboss.netty.util.internal;
<a class="jxr_linenumber" name="24" href="#24">24</a>  
<a class="jxr_linenumber" name="25" href="#25">25</a>  <strong class="jxr_keyword">import</strong> java.util.Random;
<a class="jxr_linenumber" name="26" href="#26">26</a>  
<a class="jxr_linenumber" name="27" href="#27">27</a>  <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="28" href="#28">28</a>  <em class="jxr_javadoccomment"> * A random number generator isolated to the current thread.  Like the</em>
<a class="jxr_linenumber" name="29" href="#29">29</a>  <em class="jxr_javadoccomment"> * global {@link Random} generator used by the {@link</em>
<a class="jxr_linenumber" name="30" href="#30">30</a>  <em class="jxr_javadoccomment"> * Math} class, a {@code ThreadLocalRandom} is initialized</em>
<a class="jxr_linenumber" name="31" href="#31">31</a>  <em class="jxr_javadoccomment"> * with an internally generated seed that may not otherwise be</em>
<a class="jxr_linenumber" name="32" href="#32">32</a>  <em class="jxr_javadoccomment"> * modified. When applicable, use of {@code ThreadLocalRandom} rather</em>
<a class="jxr_linenumber" name="33" href="#33">33</a>  <em class="jxr_javadoccomment"> * than shared {@code Random} objects in concurrent programs will</em>
<a class="jxr_linenumber" name="34" href="#34">34</a>  <em class="jxr_javadoccomment"> * typically encounter much less overhead and contention.  Use of</em>
<a class="jxr_linenumber" name="35" href="#35">35</a>  <em class="jxr_javadoccomment"> * {@code ThreadLocalRandom} is particularly appropriate when multiple</em>
<a class="jxr_linenumber" name="36" href="#36">36</a>  <em class="jxr_javadoccomment"> * tasks use random numbers in parallel in thread pools.</em>
<a class="jxr_linenumber" name="37" href="#37">37</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="38" href="#38">38</a>  <em class="jxr_javadoccomment"> * &lt;p&gt;Usages of this class should typically be of the form:</em>
<a class="jxr_linenumber" name="39" href="#39">39</a>  <em class="jxr_javadoccomment"> * {@code ThreadLocalRandom.current().nextX(...)} (where</em>
<a class="jxr_linenumber" name="40" href="#40">40</a>  <em class="jxr_javadoccomment"> * {@code X} is {@code Int}, {@code Long}, etc).</em>
<a class="jxr_linenumber" name="41" href="#41">41</a>  <em class="jxr_javadoccomment"> * When all usages are of this form, it is never possible to</em>
<a class="jxr_linenumber" name="42" href="#42">42</a>  <em class="jxr_javadoccomment"> * accidently share a {@code ThreadLocalRandom} across multiple threads.</em>
<a class="jxr_linenumber" name="43" href="#43">43</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="44" href="#44">44</a>  <em class="jxr_javadoccomment"> * &lt;p&gt;This class also provides additional commonly used bounded random</em>
<a class="jxr_linenumber" name="45" href="#45">45</a>  <em class="jxr_javadoccomment"> * generation methods.</em>
<a class="jxr_linenumber" name="46" href="#46">46</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="47" href="#47">47</a>  <em class="jxr_javadoccomment"> * @since 1.7</em>
<a class="jxr_linenumber" name="48" href="#48">48</a>  <em class="jxr_javadoccomment"> */</em>
<a class="jxr_linenumber" name="49" href="#49">49</a>  <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">class</strong> <a href="../../../../../org/jboss/netty/util/internal/ThreadLocalRandom.html">ThreadLocalRandom</a> <strong class="jxr_keyword">extends</strong> Random {
<a class="jxr_linenumber" name="50" href="#50">50</a>      <em class="jxr_comment">// same constants as Random, but must be redeclared because private</em>
<a class="jxr_linenumber" name="51" href="#51">51</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">long</strong> multiplier = 0x5DEECE66DL;
<a class="jxr_linenumber" name="52" href="#52">52</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">long</strong> addend = 0xBL;
<a class="jxr_linenumber" name="53" href="#53">53</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">long</strong> mask = (1L &lt;&lt; 48) - 1;
<a class="jxr_linenumber" name="54" href="#54">54</a>  
<a class="jxr_linenumber" name="55" href="#55">55</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="56" href="#56">56</a>  <em class="jxr_javadoccomment">     * The random seed. We can't use super.seed.</em>
<a class="jxr_linenumber" name="57" href="#57">57</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="58" href="#58">58</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">long</strong> rnd;
<a class="jxr_linenumber" name="59" href="#59">59</a>  
<a class="jxr_linenumber" name="60" href="#60">60</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="61" href="#61">61</a>  <em class="jxr_javadoccomment">     * Initialization flag to permit the first and only allowed call</em>
<a class="jxr_linenumber" name="62" href="#62">62</a>  <em class="jxr_javadoccomment">     * to setSeed (inside Random constructor) to succeed.  We can't</em>
<a class="jxr_linenumber" name="63" href="#63">63</a>  <em class="jxr_javadoccomment">     * allow others since it would cause setting seed in one part of a</em>
<a class="jxr_linenumber" name="64" href="#64">64</a>  <em class="jxr_javadoccomment">     * program to unintentionally impact other usages by the thread.</em>
<a class="jxr_linenumber" name="65" href="#65">65</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="66" href="#66">66</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">boolean</strong> initialized;
<a class="jxr_linenumber" name="67" href="#67">67</a>  
<a class="jxr_linenumber" name="68" href="#68">68</a>      <em class="jxr_comment">// Padding to help avoid memory contention among seed updates in</em>
<a class="jxr_linenumber" name="69" href="#69">69</a>      <em class="jxr_comment">// different TLRs in the common case that they are located near</em>
<a class="jxr_linenumber" name="70" href="#70">70</a>      <em class="jxr_comment">// each other.</em>
<a class="jxr_linenumber" name="71" href="#71">71</a>      @SuppressWarnings(<span class="jxr_string">"unused"</span>)
<a class="jxr_linenumber" name="72" href="#72">72</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">long</strong> pad0, pad1, pad2, pad3, pad4, pad5, pad6, pad7;
<a class="jxr_linenumber" name="73" href="#73">73</a>  
<a class="jxr_linenumber" name="74" href="#74">74</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="75" href="#75">75</a>  <em class="jxr_javadoccomment">     * The actual ThreadLocal</em>
<a class="jxr_linenumber" name="76" href="#76">76</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="77" href="#77">77</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">final</strong> ThreadLocal&lt;ThreadLocalRandom&gt; localRandom =
<a class="jxr_linenumber" name="78" href="#78">78</a>          <strong class="jxr_keyword">new</strong> ThreadLocal&lt;ThreadLocalRandom&gt;() {
<a class="jxr_linenumber" name="79" href="#79">79</a>              @Override
<a class="jxr_linenumber" name="80" href="#80">80</a>              <strong class="jxr_keyword">protected</strong> <a href="../../../../../org/jboss/netty/util/internal/ThreadLocalRandom.html">ThreadLocalRandom</a> initialValue() {
<a class="jxr_linenumber" name="81" href="#81">81</a>                  <strong class="jxr_keyword">return</strong> <strong class="jxr_keyword">new</strong> <a href="../../../../../org/jboss/netty/util/internal/ThreadLocalRandom.html">ThreadLocalRandom</a>();
<a class="jxr_linenumber" name="82" href="#82">82</a>              }
<a class="jxr_linenumber" name="83" href="#83">83</a>      };
<a class="jxr_linenumber" name="84" href="#84">84</a>  
<a class="jxr_linenumber" name="85" href="#85">85</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="86" href="#86">86</a>  <em class="jxr_javadoccomment">     * Returns the current thread's {@code ThreadLocalRandom}.</em>
<a class="jxr_linenumber" name="87" href="#87">87</a>  <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="88" href="#88">88</a>  <em class="jxr_javadoccomment">     * @return the current thread's {@code ThreadLocalRandom}</em>
<a class="jxr_linenumber" name="89" href="#89">89</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="90" href="#90">90</a>      <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">static</strong> <a href="../../../../../org/jboss/netty/util/internal/ThreadLocalRandom.html">ThreadLocalRandom</a> current() {
<a class="jxr_linenumber" name="91" href="#91">91</a>          <strong class="jxr_keyword">return</strong> localRandom.get();
<a class="jxr_linenumber" name="92" href="#92">92</a>      }
<a class="jxr_linenumber" name="93" href="#93">93</a>  
<a class="jxr_linenumber" name="94" href="#94">94</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="95" href="#95">95</a>  <em class="jxr_javadoccomment">     * Throws {@code UnsupportedOperationException}.  Setting seeds in</em>
<a class="jxr_linenumber" name="96" href="#96">96</a>  <em class="jxr_javadoccomment">     * this generator is not supported.</em>
<a class="jxr_linenumber" name="97" href="#97">97</a>  <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="98" href="#98">98</a>  <em class="jxr_javadoccomment">     * @throws UnsupportedOperationException always</em>
<a class="jxr_linenumber" name="99" href="#99">99</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="100" href="#100">100</a>     @Override
<a class="jxr_linenumber" name="101" href="#101">101</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> setSeed(<strong class="jxr_keyword">long</strong> seed) {
<a class="jxr_linenumber" name="102" href="#102">102</a>         <em class="jxr_comment">// We rely on the fact that the superclass no-arg constructor</em>
<a class="jxr_linenumber" name="103" href="#103">103</a>         <em class="jxr_comment">// invokes setSeed exactly once to initialize.</em>
<a class="jxr_linenumber" name="104" href="#104">104</a>         <strong class="jxr_keyword">if</strong> (initialized) {
<a class="jxr_linenumber" name="105" href="#105">105</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> UnsupportedOperationException();
<a class="jxr_linenumber" name="106" href="#106">106</a>         }
<a class="jxr_linenumber" name="107" href="#107">107</a>         initialized = <strong class="jxr_keyword">true</strong>;
<a class="jxr_linenumber" name="108" href="#108">108</a>         rnd = (seed ^ multiplier) &amp; mask;
<a class="jxr_linenumber" name="109" href="#109">109</a>     }
<a class="jxr_linenumber" name="110" href="#110">110</a> 
<a class="jxr_linenumber" name="111" href="#111">111</a>     @Override
<a class="jxr_linenumber" name="112" href="#112">112</a>     <strong class="jxr_keyword">protected</strong> <strong class="jxr_keyword">int</strong> next(<strong class="jxr_keyword">int</strong> bits) {
<a class="jxr_linenumber" name="113" href="#113">113</a>         rnd = rnd * multiplier + addend &amp; mask;
<a class="jxr_linenumber" name="114" href="#114">114</a>         <strong class="jxr_keyword">return</strong> (<strong class="jxr_keyword">int</strong>) (rnd &gt;&gt;&gt; 48 - bits);
<a class="jxr_linenumber" name="115" href="#115">115</a>     }
<a class="jxr_linenumber" name="116" href="#116">116</a> 
<a class="jxr_linenumber" name="117" href="#117">117</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">long</strong> serialVersionUID = -5851777807851030925L;
<a class="jxr_linenumber" name="118" href="#118">118</a> }
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